The organic solar cell, as a potential renewable energy, has attracted wide attention, which has some incomparable advantages better than inorganic solar cell, such as low cost, simple manufacturing process, light-weight, and it can be made flexibly in great area and so on. Over the past decade, the performance of the organic solar cell has improved, and the energy conversion efficiency is close to 10%.
The energy conversion efficiency of the organic solar cell has improved greatly; however, so far, the energy conversion efficiency of the organic solar cell is much lower than that of the inorganic solar cell. Therefore, in order to make the organic solar cell be implemented commercially, it is significant to develop a new organic semiconductor material for improving the efficiency of the organic solar cell.
In recent years, due to the development of the conjugated polymers in the design and the fabrication process of the device, the efficiency of the polymer solar cell has remarkably improved. In future, one challenge of the polymer solar cell is to synthesize a new P-type-conjugated polymer, which needs to have features of: (a) good solubility, which facilitates for processing and performing industrial production; (b) broad and strong absorption to the entire solar spectrum; (c) high carrier mobility, which facilitates for carrier transport. The researches have focused on broadening the light absorption range of the polymer materials and making the light absorption maximally cover the entire spectrum of solar light. Choosing an appropriate monomer in the semiconductor polymer backbone can broaden the light absorption range to infrared and near infrared. However, it fails to find such appropriate monomer in the prior art.